No, that’s a matter of making the job easier, and thus cheaper. Probably wasn’t the artists coming up with the idea, as you say. I assume as animators they want to create new art. But if a line producer is given a tight budget, it would make sense (to that producer) to reuse whatever assets they could get away with.
I don’t believe the original rotoscopes were acquired with an eye toward reuse in future cartoons. If they were rotoscopes at all, they were of actors performing specific scripted actions for a specific script. Later-period Disney movies were just made on the cheap, wherever they could economize like this and get away with it. That’s all.
